Duplexer

ABSTRACT

A duplexer according to the present invention includes: an acoustic wave element having a first terminal and a second terminal; a substrate mounting the acoustic wave element on the surface; a first columnar conductor electrically connected to the first terminal, and drawn to a back surface of the substrate, while being buried partially in the substrate; a second columnar conductor electrically connected to the second terminal, and drawn to the back surface of the substrate, while being buried partially in the substrate; a first ground pattern region arranged between the first columnar conductor drawn part and the second columnar conductor drawn part on the back surface of the substrate; a second ground pattern region electrically connected to the first ground pattern region on the back surface of the substrate and arranged in the part not including the part between the first columnar conductor drawn part and the second columnar conductor drawn part; and a third columnar conductor electrically connected to the first ground pattern region, while being buried partially in the substrate.

BACKGROUND OF THE INVENTION

The present application claims the priority of Japanese PatentApplication No. 2007-257302 filed on Oct. 1, 2007 in Japan and JapanesePatent Application No. 2008-113564 filed on Apr. 24, 2008 in Japan, andthe contents of which are incorporated herein by references.

1. Technical Field

The present invention relates to a duplexer used in a mobile phone andthe like.

2. Background Art

As shown in FIG. 14, conventionally, this kind of duplexer includes anacoustic wave element 1 having an antenna terminal 1A, a receptionterminal 1B, and a transmission terminal (not shown), and a ceramicsubstrate 2 on which the acoustic wave element 1 is set. The substrate 2internally has a columnar conductor 2A electrically connected to theantenna terminal 1A and drawn to a back surface of the substrate 2, acolumnar conductor 2B electrically connected to the reception terminal1B and drawn to the back surface of the substrate 2, and a columnarconductor (not shown) electrically connected to the transmissionterminal (not shown) and drawn to the back surface of the substrate 2.Since a ground pattern is not provided between the drawn part of thecolumnar conductor 2A and the drawn part of the columnar conductor 2B onthe back surface of the substrate 2, a solder and the like prevents ashort circuit from generating between the drawn part of the columnarconductor 2A and the drawn part of the columnar conductor 2B.

In addition, Japanese Patent Laid-open Publication No. 2000-49565 isknown as a conventional art document information relating to thisapplication.

SUMMARY OF THE INVENTION

The above-described duplexer has had a problem in low isolation.

More specifically, in the above conventional configuration, whenelectromagnetic field coupling is generated between the drawn part ofthe columnar conductor 2A and the drawn part of the columnar conductor2B, for example, a signal is transmitted from the columnar conductor 2Ato the columnar conductor 2B due to the electromagnetic field coupling,and as a result, its isolation becomes problematically low.

Thus, it is an object of the present invention to improve isolation of aduplexer.

Thus, in order to achieve the above object, the present inventionprovides a configuration having a first ground pattern region arrangedbetween a first columnar conductor drawn part and a second columnarconductor drawn part on a back surface of a substrate, a second groundpattern region electrically connected to the first ground pattern regionon the back surface of the substrate, and arranged in a part notincluding between the first columnar conductor drawn part and the secondcolumnar conductor drawn part, a third columnar conductor electricallyconnected to the first ground pattern region, while being buriedpartially in the substrate, and an insulating coating formed on asurface to which the first ground pattern region is exposed.

In the above configuration, the insulation coating prevents a shortcircuit from generating between the first columnar conductor drawn partand the second columnar conductor drawn part, and the third columnarconductor electrically connected to the second ground pattern regionthrough the first ground pattern region prevents electromagnetic fieldcoupling from generating between the first columnar conductor and thesecond columnar conductor, and as a result, isolation of the duplexercan be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become readily understood from the followingdescription of preferred embodiments thereof made with reference to theaccompanying drawings, in which like parts are designated by likereference numeral and in which:

FIG. 1 is a top view of an acoustic wave element in a duplexer accordingto a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of the duplexer according to the firstembodiment of the present invention;

FIG. 3 is a cross-sectional view taken along a line B-BB in FIG. 2;

FIG. 4 is a cross-sectional view taken along a line C-CC in FIG. 2;

FIG. 5 is a cross-sectional view taken along a line D-DD in FIG. 2;

FIG. 6 is a bottom view of the duplexer according to the firstembodiment of the present invention;

FIG. 7 is a cross-sectional view taken along a line E-EE in FIG. 2;

FIG. 8 is a cross-sectional view taken along a line C-CC in FIG. 2;.

FIG. 9 is a cross-sectional view taken along a line B-BB in FIG. 2;

FIG. 10 is a bottom view of the duplexer according to the firstembodiment of the present invention;

FIG. 11 is a bottom view of the acoustic wave element of the duplexeraccording to the first embodiment of the present invention;

FIG. 12 is a cross-sectional view showing another embodiment of theduplexer according to the first embodiment of the present invention;

FIG. 13 is a frequency property diagram of the duplexer according to thefirst embodiment of the present invention; and

FIG. 14 is a cross-sectional view of a conventional duplexer.

EXPLANATION OF REFERENCES

-   ACOUSTIC WAVE ELEMENT-   4A FIRST TERMINAL (ANTENNA TERMINAL)-   4B SECOND TERMINAL (RECEPTION TERMINAL)-   SUBSTRATE-   5A FIRST COLUMNAR CONDUCTOR-   5B SECOND COLUMNAR CONDUCTOR-   5C THIRD COLUMNAR CONDUCTOR-   6A FIRST COLUMNAR CONDUCTOR DRAWN PART-   6B SECOND COLUMNAR CONDUCTOR DRAWN PART-   7 INSULATING COATING-   8A FIRST GROUND PATTERN REGION-   8B SECOND GROUND PATTERN REGION

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

Hereinafter, a duplexer according to a first embodiment of the presentinvention will be described with reference to the drawings.

As shown in FIG. 1, the duplexer according to this embodiment includesan acoustic wave element 4 having an antenna terminal 4A serving as afirst terminal, reception terminals 4B and 4D serving as secondterminals, and a transmission terminal 4C on its lower side and as shownin FIG. 2, a substrate 5 on which the acoustic wave element 4 is set. Inaddition, the duplexer according to this first embodiment outputsreception signals as a balanced output with the reception terminals 4Band 4D. Here, FIG. 2 is a cross-sectional view showing the wholeduplexer taken along a line A-AA in FIG. 1.

Thus, the substrate 5 internally has a first columnar (pillar or via)conductor 5A having at least one embedded part therein, electricallyconnected to the antenna terminal 4A, and drawn to a back surface of thesubstrate 5, and a second columnar conductor 5B and a fifth columnarconductor 5E electrically connected to the reception terminals 4B and 4Drespectively, while each being partially buried in the substrate 5, anddrawn to the back surface of the substrate 5 similarly. A crosssectional view taken along a line B-BB in FIG. 2 is shown in FIG. 3, anda cross section taken along a line A-AA in FIG. 3 corresponds to FIG.

2.

Thus, as shown in FIG. 4 as a cross-sectional view taken along a lineC-CC in FIG. 2, the back surface of the substrate 5 includes a firstground pattern region 8A arranged in a region sandwiched by two dottedlines which are parallel to a straight line connecting the drawn part ofthe first columnar conductor 5A and the drawn part of the secondcolumnar conductor 5B, and a second ground pattern region 8Belectrically connected to the first ground pattern region 8A, andarranged in the region not including the region sandwiched by the abovetwo dotted lines between the drawn part of the first columnar conductor5A and the drawn part of the second columnar conductor 5B.

Thus, a third columnar conductor 5C is formed so as to be electricallyconnected to the first ground pattern region 8A as shown in FIG. 4, andembedded in the substrate 5 as shown in FIG. 2. In this configuration,the third columnar conductor 5C is at roughly the ground potential.

Thus, an insulation coating 7 is provided on a surface to which thefirst ground pattern region 8A is exposed as shown in FIG. 5 as asectional view taken along a line D-DD in FIG. 2. A first columnarconductor drawn part 6A, a second columnar conductor drawn part 6B, andthe second ground pattern region 8B are exposed from parts 7A, 7B, and7C, respectively, in which the insulating coating is not provided, asshown in FIG. 6 as a bottom view of the duplexer shown in FIG. 2. Inaddition, a fifth columnar conductor drawn part 6E electricallyconnected to the reception terminal 4D through the fifth columnarconductor 5E is also exposed. In other words, the duplexer outputs thereception signals as a balanced output with the second columnarconductor drawn part 6B and the fifth columnar conductor drawn part 6E.

In addition, since FIG. 6 is a bottom view, it is a mirror-reversed viewof FIG. 5 as the cross-sectional view taken from the top of theduplexer.

In addition, the transmission terminal 4C shown in FIG. 1 iselectrically connected to a columnar conductor 5D shown in FIG. 3, inthe substrate 5 shown in FIG. 2, and as shown in FIG. 6, its drawn part6D is exposed from the part in which the insulation coating 7 is notformed in the back surface of the substrate 5.

Thus, as shown in FIG. 6, the insulation coating 7 prevents a shortcircuit from generating between the first columnar conductor drawn part6A and the second columnar conductor drawn part 6B, and as shown in FIG.4, the third columnar conductor 5C electrically connected to the secondground pattern region 8B through the first ground pattern region 8Aprevents electromagnetic field coupling from generating between thefirst columnar conductor 5A and the second columnar conductor 5B. As aresult, the isolation of the duplexer can be improved.

More specifically, when the second columnar conductor drawn part 6B andthe fifth columnar conductor drawn part 6E which output the receptionsignal as the balanced outputs are different in distance to the firstcolumnar conductor drawn part 6A electrically connected to the antennaterminal 4A, a coupling degree between the second columnar conductordrawn part 6B and the first columnar conductor drawn part 6A isdifferent from a coupling degree between the fifth columnar conductordrawn part 6E and the first columnar conductor drawn part 6A, so thatthe balance properties of the reception signals outputted from thecolumnar conductor drawn parts 6B and 6E deteriorate.

Thus, the third columnar conductor 5C electrically connected to thefirst ground pattern region 8A prevents the electromagnetic fieldcoupling from generating between the first columnar conductor 5A and thesecond columnar conductor 5B, and as a result, the balance properties ofthe reception signals outputted from the columnar conductor drawn parts6B and 6E can be improved. Thus, attenuation properties in atransmission band can be improved.

In addition, by setting a density of the columnar conductor electricallyconnected to the first ground pattern region 8A higher than a density ofthe columnar conductor electrically connected to the second groundpattern region, the balance properties of the reception signalsoutputted from the columnar conductor drawn parts 6B and 6E can be alsoimproved. Thus, the attenuation properties in the transmission band canbe improved.

Moreover, by setting the density of the columnar conductor electricallyconnected to the first ground pattern region 8A higher than a density ofa columnar conductor electrically connected to a fourth ground patternregion 8C arranged in a region sandwiched by two thick lines which areparallel to the straight line connecting between the drawn part of thefirst columnar conductor 5A and the fifth columnar conductor 5E on theback surface of the substrate, the balance properties of the receptionsignals outputted from the columnar conductor drawn parts 6B and 6E(FIG. 4) can be further improved (FIG. 4). Thus, the attenuationproperties in the transmission band can be further improved. Inaddition, as shown in FIG. 4, the first ground pattern region 8A and thefourth ground pattern region 8C are partially overlapped.

Still furthermore, by setting the number of the columnar conductorselectrically connected to the first ground pattern region 8A greaterthan the number of the columnar conductors electrically connected to thefourth ground pattern region 8C, the balance properties of the receptionsignals outputted from the columnar conductor drawn parts 6B and 6E canbe improved. As a result, the attenuation properties in the transmissionband can be further improved.

In addition, according to this embodiment, as shown in FIG. 2, theantenna terminal 4A and the reception terminal 4B are electricallyconnected to the first and second columnar conductors 5A and 5B,respectively through solder bumps 8, columnar conductors 9A and 9B andan electrode pattern 10 shown in FIG. 7 as a cross-sectional view takenalong a line E-EE in FIG. 2. Thus, when the electrode pattern 10 isinterposed in the substrate 5, the positions of the first columnarconductor drawn part 6A and the second columnar conductor drawn part 6Bare not limited to the positions of the antenna terminal 4A and thetransmission terminal 4B in the acoustic wave element, so that a degreeof design freedom is enhanced.

In addition, according to this embodiment, as shown in FIG. 8, the thirdcolumnar conductor 5C is electrically connected to a shortest linesegment 16 connecting the first columnar conductor drawn part 6A and thesecond columnar conductor drawn part 6B in the first ground patternregion 8A. In this configuration, the electromagnetic field coupling canbe more effectively prevented from generating between the first columnarconductor drawn part 6A and the second columnar conductor drawn part 6B,and as a result, the isolation of the duplexer can be efficientlyimproved.

Furthermore, as shown in FIG. 9, it is desirable that the third columnarconductor 5C is arranged in a plane 9 containing the first columnarconductor 5A and the second columnar conductor 5B because theelectromagnetic field coupling can be more effectively prevented fromgenerating between the first columnar conductor 5A and the secondcolumnar conductor 5B, and as a result, the isolation of the duplexercan be improved. In addition, when the second columnar conductor drawnpart 6B and the fifth columnar conductor drawn part 6E which output thereception signals as the balanced output are different in distance tothe first columnar conductor drawn part 6A electrically connected to theantenna terminal 4A, this configuration can improve the balanceproperties of the reception signals outputted from the columnarconductor drawn parts 6B and 6E. As a result, the attenuation propertiesin the transmission band can be improved.

In addition, a description will be made of a problem arising in a casewhere the duplexer has a function to output a balanced signal, that is,in a case where the reception terminal 4B shown in FIG. 2 is a firstbalanced output terminal, the acoustic wave element has a secondbalanced output terminal (not shown) as a third terminal, and a fourthcolumnar conductor (not shown) having at least one part embedded in thesubstrate 5, electrically connected to the second balanced outputterminal (not shown), and drawn to the back surface of the substrate 5is provided. In the above case, since both of the second columnarconductor drawn part 6B and the fourth columnar conductor drawn part(not shown) are exposed onto the back surface of the substrate 5 havinga limited area, either one of the second columnar conductor drawn part6B and the fourth columnar conductor drawn part (not shown) isinevitably close to the first columnar conductor drawn part 6A shown inFIG. 6, so that there is concern that the isolation could be lowered. Inthis case, as shown in FIG. 4 in the above embodiment, the thirdcolumnar conductor 5C electrically connected to the second groundpattern region 8B through the first ground pattern region 8A can preventthe electromagnetic field coupling from generating between the firstcolumnar conductor 5A and the second columnar conductor 5B, and as aresult, the isolation of the duplexer can be improved.

Furthermore, as described above, when the acoustic wave element has thefirst and second balanced output terminals (not shown), a desirableeffect can be produced when the drawn parts (not shown) of them on theback surface of the substrate 5 are arranged on the same one side in theback surface of the substrate 5 because a connection wiring with anothercomponent can be facilitated on a module substrate (not shown) mountingthis duplexer.

In addition, as shown in FIG. 10, the first columnar conductor drawnpart 6A electrically connected to the antenna terminal 4A (refer toFIGS. 1 and 2) is arranged in the center of a first side 10A. Inaddition, the drawn part 6B of the second columnar conductor 5Belectrically connected to the reception terminal 4B (refer to FIGS. 1and 2) is arranged on a second side 10B roughly perpendicular to thefirst side 10A in the substrate 5. Furthermore, the drawn part 6D of thefourth columnar conductor (not shown) electrically connected to thetransmission terminal 4C (refer to FIG. 1) is arranged on a third side10D roughly perpendicular to the first side 10A in the substrate 5. Inthe above configuration, the electromagnetic field coupling can beprevented from generating between the antenna terminal 4A (refer toFIGS. 1 and 2) and the reception terminal 4B (refer to FIGS. 1 and 2),and between the antenna terminal 4A (refer to FIGS. 1 and 2) and thetransmission terminal 4C (refer to FIG. 1) and the isolation of theduplexer can be improved.

Furthermore, as shown in FIG. 11 as a bottom view of the acoustic waveelement 4, when the acoustic wave element includes a DMS (double-modesurface acoustic wave) filter 11, as shown in FIG. 12, it is preferablethat a third ground pattern 12 is formed in the substrate 5, and fifthcolumnar conductors 13A and 13B electrically connected to fourth groundpatterns 14A and 14B of the DMS filter 11 shown in FIG. 11 areelectrically connected to the third ground pattern 12.

In the above configuration, a parasitic component interposed between theDMS filter 11 and the ground potential can be prevented from generating,and as a result, common mode properties can be improved as shown in FIG.13.

In addition, when two or more DMS filters are connected, as shown inFIG. 11, by connecting a fifth columnar conductor 13C electricallyconnected to a fourth ground pattern 14C formed between the two DMSfilters, to the third ground pattern 12, the above effect can be furtherimproved.

A duplexer according to the present invention produces an effect thatisolation can be improved, and can be useful in various electronicdevices such as a mobile phone and the like.

1. A duplexer comprising: an acoustic wave element having a firstterminal and a second terminal; a substrate mounting the acoustic waveelement on the surface; a first columnar conductor electricallyconnected to the first terminal, and drawn to a back surface of thesubstrate, while being buried partially in the substrate; a secondcolumnar conductor electrically connected to the second terminal, anddrawn to the back surface of the substrate, while being buried partiallyin the substrate; a first ground pattern region arranged between thefirst columnar conductor drawn part and the second columnar conductordrawn part, on the back surface of the substrate; a second groundpattern region electrically connected to the first ground pattern regionand arranged in the part not including between the first columnarconductor drawn part and the second columnar conductor drawn part, onthe back surface of the substrate; and a third columnar conductorelectrically connected to the first ground pattern region, while beingburied partially in the substrate.
 2. The duplexer according to claim 1,further comprising an insulating coating formed on a surface having theexposed first ground pattern region.
 3. The duplexer according to claim1, wherein the third columnar conductor is electrically connected to ashortest line segment connecting the first columnar conductor drawn partand the second columnar conductor drawn part, in the first groundpattern region.
 4. The duplexer according to claim 1, wherein the thirdcolumnar conductor is formed in a plane containing the first columnarconductor and the second columnar conductor.
 5. The duplexer accordingto claim 1, wherein the acoustic wave element has a third terminal, andfurther comprising a fourth columnar conductor electrically connected tothe third terminal, and drawn to the back surface of the substrate,while being buried partially in the substrate.
 6. The duplexer accordingto claim 5, wherein the second terminal is a first balanced outputterminal, the third terminal is a second balanced output terminal, andthe second columnar conductor drawn part and the fourth columnarconductor drawn part are arranged on the same side in the substrate. 7.The duplexer according to claim 5, wherein the first terminal is anantenna terminal, and the second terminal is a reception terminal, andthe third terminal is a transmission terminal, wherein the firstcolumnar conductor drawn part is arranged in roughly the center of afirst side in the substrate, the second columnar conductor drawn part isarranged on a second side roughly perpendicular to the first side in thesubstrate, and the fourth columnar conductor drawn part is arranged on athird side roughly perpendicular to the first side in the substrate. 8.The duplexer according to claim 1, wherein the acoustic wave element hasa DMS filter, wherein a fifth columnar conductor is electricallyconnected to a ground pattern in the DMS filter, and a third groundpattern region electrically connected to the fifth columnar conductor isprovided in the substrate.
 9. A duplexer comprising: an acoustic waveelement having an antenna terminal and two balanced output receptionterminals, and a transmission terminal; a substrate mounting theacoustic wave element on the surface; a first columnar conductorelectrically connected to the antenna terminal and drawn to a backsurface of the substrate; a second columnar conductor electricallyconnected to one of the reception terminals, and drawn to the backsurface of the substrate, while being buried partially in the substrate;a fourth columnar conductor electrically connected to the other of thereception terminals, and drawn to the back surface of the substrate,while being buried partially in the substrate; a first ground patternregion arranged between the first columnar conductor drawn part and thesecond columnar conductor drawn part, on the back surface of thesubstrate; and a second ground pattern region electrically connected tothe first ground pattern region and arranged in the part not includingthe part between the first columnar conductor drawn part and the secondcolumnar conductor drawn part, on the back surface of the substrate,wherein if the second columnar conductor drawn part and the fourthcolumnar conductor drawn part are different in distance to the firstcolumnar conductor drawn part, a density of a columnar conductorelectrically connected to the first ground pattern region is set higherthan a density of a columnar conductor electrically connected to thesecond ground pattern region.
 10. A duplexer comprising: an acousticwave element having an antenna terminal and two balanced outputreception terminals, and a transmission terminal; a substrate having theacoustic wave element set thereon; a first columnar conductorelectrically connected to the antenna terminal and drawn to a backsurface of the substrate; a second columnar conductor electricallyconnected to one of the reception terminals, and drawn to the backsurface of the substrate, while being buried partially in the substrate;and a fourth columnar conductor electrically connected to the other ofthe reception terminals, and drawn to the back surface of the substrate,while being buried partially in the substrate; a first ground patternregion arranged between the first columnar conductor drawn part and thesecond columnar conductor drawn part on the back surface of thesubstrate, and a fourth ground pattern region arranged between the firstcolumnar conductor drawn part and the fourth columnar conductor drawnpart on the back surface of the substrate, wherein if the secondcolumnar conductor drawn part and the fourth columnar conductor drawnpart are different in distance to the first columnar conductor drawnpart, a density of a columnar conductor electrically connected to thefirst ground pattern region is set higher than a density of a columnarconductor electrically connected to the fourth ground pattern region.